With rapid development of an electronic communication technology, a peripheral device attached to or additionally used for an electronic device also develops. For example, for the peripheral device, there exists an auxiliary memory card, an ear microphone mounted and installed in an electronic device to allow communication with a counterpart user, a Bluetooth headset for performing short distance wireless communication via a Bluetooth module mounted in the electronic device, and a stylus pen which is a kind of a digital pen used to manipulate a touchscreen unit for performing input and output simultaneously.
Recently, a so-called smartphone is mainly used as a representative electronic device, and the smartphone indispensably has a touchscreen unit performing input/output of data simultaneously using a large-sized screen with consideration of use convenience.
A touch panel used for the touchscreen unit is roughly classified into various touch panels such as a resistive touch panel, a capacitive touch panel, an ultrasonic touch panel, a light (infrared) sensor type touch panel, a touch panel using an electromagnetic resonance, etc.
To increase convenience and variety in touch, the electronic device having the above-described various types of touchscreen unit has a stylus pen of a predetermined length, whose end has a pointed tip so that it is detachable from the inside of the electronic device. For example, an electronic device having a resistive touchscreen may have a construction where a stylus pen has a simply pointed end and touches the touchscreen with a predetermined pressure. Also, in a case of a capacitive touch panel, it is preferable that a tip contacting the touchscreen is formed of a conductive material and applied.
Meanwhile, a method using an electromagnetic resonance requires a sensor pad (referred to as a ‘digitizer’) arranged in an array configuration for generating electromagnetic resonance at the lower portion of a display screen on which pen input is performed, and detection is possible only within a detect region of the sensor pad.
However, since this method requires a magnetic material and a coil body inside a pen and requires a flat-shaped sensor pad also inside an electronic device, the structure is complicated and manufacturing costs increase. Also, in the method using an ultrasonic wave, when a pen generates an ultrasonic wave, a time until a receiver provided to an electronic device receives the ultrasonic wave is measured, and a distance between the receiver and the pen is calculated from the propagation velocity of an ultrasonic wave and the time until the ultrasonic wave is received. Therefore, unlike the electromagnetic resonance method, the method using the ultrasonic wave does not require the sensor pad of array configuration and the detect region is relatively wide. The above-described related-art ultrasonic wave method uses a method of measuring distances between two or more receivers and a pen, and calculating the coordinate of the pen using triangle drawing. This method may accurately measure a time until an ultrasonic wave is received only when a receiver knows an accurate point at which the pen generates the ultrasonic wave. Therefore, there is a need for a more reasonable measurement method.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.